High-Mn austenitic stainless steel for hydrogen having excellent weldability, welded joint using same, device for hydrogen using same, and method for producing welded joint

Abstract

This austenitic stainless steel contains, by mass %: C: 0.3% or less, Si: 0.1% to 1.5%, Mn: 5.5% to 20%, P: 0.050% or less, S: 0.005% or less, Cr: 10% to 20%, Ni: 4.0% to 12%, N: 0.40% or less, Cu: 4.0% or less, O: 0.02% or less, and either one or both of Ca: 0.01% or less and Al: 0.3% or less, with a remainder being Fe and inevitable impurities, and the following Formula (1) is satisfied.[Ni]+[Cu]+12.93[C]+1.11[Mn]+0.72[Cr]+0.88[Mo]−0.27[Si]+7.55[N]≥29.3   Formula (1)

Description

TECHNICAL FIELD[0001]The present invention relates to an austenitic stainless steel which is used in a high-pressure hydrogen gas and liquid hydrogen environment and has excellent weldability and hydrogen embrittlement resistance characteristics (resistance to hydrogen embrittlement), a welded joint using the austenitic stainless steel, a device for hydrogen using the austenitic stainless steel, and a method for producing a welded joint.[0002]The present application claims priority on Japanese Patent Application No. 2017-069239 filed on Mar. 30, 2017, the content of which is incorporated herein by reference.BACKGROUND ART[0003]In recent years, technologies using hydrogen as energy have been developed to suppress greenhouse gas (CO2, NOx, SOx) emission from the viewpoint of global warming prevention. From such a background, development of metal materials to be used for storing and transporting hydrogen has been expected.[0004]In Japan, marketing of fuel cell vehicles has been started...

AI Technical Summary

Benefits of technology

[0034]According to an aspect of the invention, it is possible to provide a high-Mn austenitic stainless steel for hydrogen having excellent non-filler weldability together with hydrogen resistance and economic efficiency. In addition, it is possible to provide a welded joint and a device for hydrogen which have excellent hydrogen resistance by using the austenitic stainless steel.

[0035]The device for hydrogen is applicable to tank bodies, liners, pipes, valves, steel sheets, heat exchangers, or the like, and contributes to an improvement of hydrogen resistance thereof.

Problems solved by technology

The SUS316 austenitic stainless steel described in the exemplary criteria is expensive since it contains a large amount of Ni and Mo which are rare metals.

Furthermore, since a solutionized material does not satisfy a tensile strength required for high-pressure hydrogen pipes, it is used after being cold-worked.

However, welds (welded portions) cannot be subjected to cold working.

However, since the Ni amount and the Cr amount of the stainless steel described in Patent Document 1 are substantially 10% or greater and 20% or greater, respectively, the stainless steel described in Patent Document 1 is expensive.

However, an additional heat treatment is required to precipitate the η-phase intermetallic compound, and it is difficult to apply this steel to a welded structure.

In addition, since it is required to add 20% or greater of Ni in the stainless steel described in Patent Document 3, the alloy cost is large.

However, this finding is on the assumption of welding with a welding material, and not on the assumption of non-filler welding with no welding material.